1. Field of the Invention
The present invention relates to an endoscope system including an endoscope having an objective optical system with a different viewing angle in an observation window at a distal end of an insertion unit, in which an installation position of a treatment instrument channel opening varies according to the viewing angle of the objective optical system.
2. Description of the Related Art
In recent years in a medical field, the endoscope device has been utilized to observe and operate organs within a body cavity by employing the endoscope which has at least a long insertion unit having the observation window, an illumination window, and the treatment instrument channel opening at its end part and an operating unit positioned at an proximal end of the insertion unit. Also, this endoscope device has been utilized in observing the inside of pipes in industrial fields.
The insertion unit of this endoscope device is comprised of a distal end portion in which the observation window, the illumination window, and the treatment instrument channel opening are provided, a bendable part adjacent to the proximal end of the distal end portion, and a flexible soft tube unit connected to the proximal end of the bendable part and a distal end of the operating unit. Also, an image guide, a light guide, and a treatment instrument channel are provided in the insertion unit. An end of the image guide is arranged in the objective optical system provided in the observation window. An end of the light guide is arranged in the illumination optical system provided in the illumination window. An end of the treatment instrument channel is communicated to the treatment instrument channel opening.
The operating unit of the endoscope device, has a bending operation knob, an eye piece, a treatment instrument insertion hole, and a universal cable. The bending operation knob enables its bendable part to be controlled as pulling a bending wire extended between the bending operation knob and the bendable part of the insertion unit. The eye piece enables an operator to view the observed region image as an ocular optical system is arranged at the proximal end of the image guide. The treatment instrument insertion hole communicates with the proximal end of the treatment instrument channel for a treatment instrument to be inserted therein. The universal cable has the built-in light guide to be connected to a light source.
Also, there is another endoscope in which a solid image element is provided at an image formation position of the objective optical system of an observation window and a signal cable sending and receiving a generated image signal as driving the solid image element is provided instead of the image guide.
Regarding the endoscope device of this type, the bendable part of the insertion unit is operated to be bent according to an internal shape of a tube to be inserted therein, the reflected light is introduced from the observed region illuminated with illumination light emitted from the illumination window of the distal end portion, and the operator observes the observed region image displayed on the eye piece of the operating unit as being transmitted by the image guide.
The viewing angle of the objective optical system of the observation window provided at the distal end portion of the insertion unit depends on observed region, and for example the objective optical system with a wide viewing angle is used to facilitate the observation of a lesioned part such as a back side of large intestine bag which is difficult to be observed. Also, a wide angle endoscope device, enabling to achieve a wide range observed region image, is proposed for example in Japanese Patent Application Laid-open No. H04-102432 Publication, wherein when the bending angle of the bendable part is limited according to the shape and size of the observed region, for example, the viewing angle of the objective optical system of the endoscope used to observe the observed region, which has a wide space and may have a large bending angle of the bendable part thereof, does not need to be widened as much, while the viewing angle of the objective optical system of the endoscope used to observe the observed region, which has a relatively narrow space and may have a small bending angle of the bendable part, is set wide.
Conventionally, the wide angle endoscope device with the wide angle objective optical system arranged in the observation window has been used so as to facilitate the observation of a lesioned part which is difficult to be observed, for example, the back side of the complex shape in the tube hole to be observed, such as a back side of large intestine bag.
On the other hand, while observing the position subject to be observed (observed region) by the endoscope device, the treatment instrument is projected from the treatment instrument channel opening toward the observed region to perform various operations such as organism system incision sampling. In the process of performing various organism system operations by this treatment instrument, the operator recognizes a physical relationship between the observed region and the treatment instrument from the position of the treatment instrument displayed by the observation figure obtained from the observation window of the distal end portion of the insertion unit to be observed at the eye piece or the observation image displayed on the monitor (hereinafter both are referred to as an observation image) and operates the treatment instrument.
In the case that the physical relationship between the actual observed region and the treatment instrument are the same, the physical relationship between the observed region and the treatment instrument in the observing image for the endoscope device, which has the objective optical system of a predetermined angle (e.g., 120 to 150 degrees) at the observation window of the distal end portion of the insertion unit and has a predetermined viewing angle, is mutually different from the physical relationship between the observed region and the treatment instrument in the observing image for the endoscope, which has the objective optical system of wider viewing angle (e.g., 151 degrees or more) at the operation window of the distal end part of the insertion unit than the viewing angle of the endoscope having the predetermined viewing angle (hereinafter referred to as a wide angle endoscope device).
That is, for example, if distances, i.e., the physical distances between the observation window and the treatment instrument at the distal end part of the insertion unit with respect to the endoscope device having the predetermined viewing angle and the wide angle endoscope device, are the same, the extent of projection of the treatment instrument projecting from the respective treatment instrument channel opening to reach the viewing angle of the objective optical system of the observation window with respect to the wide angle endoscope device is smaller than the extent of the projection with respect to the endoscope device having the predetermined viewing angle. That is, the wide angle endoscope device, because of the wide angle objective optical system of the observation window, reaches the viewing angle of the wide angle objective optical system while the amount of projection of the treatment instrument projecting from the treatment instrument channel is being small.
Therefore, when the operator operates the treatment instrument with the observation image of the wide angle endoscope, the treatment instrument appears in the observation image at the position where the treatment instrument slightly projects from the treatment instrument channel opening. As such, the operator may misunderstand that the treatment instrument projects to the same position for the endoscope with the predetermined viewing angle. Accordingly, there is a problem that the operator feels uncomfortable because of the difference in the physical relationship of the treatment instrument between the endoscope device with the predetermined viewing angle and the wide angle endoscope device.
Furthermore, generally, a fixed focus optical system is used in the objective optical system provided in the observation window of the endoscope. Therefore, especially, regarding the wide angle objective optical system, surrounding of the viewing angle comparing to the central part of the viewing angle slightly becomes out of focus. Accordingly, the treatment instrument immediately after being projected in the viewing angle of the wide angle objective optical system of the wide angle endoscope device temporary becomes unclear which possibly gives uncomfortable feeling to the operator.